Abstract
The nonavailability of fossil fuels and the shortcomings of nonconventional energy sources taking place in the environment lead the research and development towards alternative and clean energy sources such as renewable energy sources. Renewable or nonconventional energy resources are being used to meet ever-increasing energy demand. The photo voltaic (PV) energy is the right choice of renewable energy for small voltage DC distribution systems, due to their advantages. But this energy source can produce low output power at the utility grid. Hence, to step up this low input voltage to high value for a range of high-voltage applications, DC-DC converters are integrated to the DC microgrids by means of PV system. The present work elaborates the modified SEPIC converter (MSC) designed based on the traditional SEPIC with a boost-up module. In comparison with conventional or traditional SEPIC converter, the proposed MSC produces high voltage gain and continuous current to the DC microgrids. Furthermore, MSC is operated with only one controlled switch. The proposed converter design improves the efficiency, output voltage, and continuous output current of the DC microgrids. This entire work is completed with PSIM, and finally, numerical simulation results prove the possibility of the MSC with PV-powered DC microgrids, and also the dynamic response of MSC for DC microgrid loads enhances the regulated output voltage and continuous output current of DC loads.
1. Introduction
Nonconventional energy sources are biomass, tidal, and geothermal energy sources that exist in nature in particular regional sectors. But solar and wind energies are abundant in nature and available in all regional sectors. Especially, solar and wind energy sources give maximum efficiency and reliability when compared with other nonconventional energy sources. Moreover, the upcoming research focuses on these two renewable energy sectors integrated to the AC and DC grids [1–3].
Normally, in the perception of the microgrid, DC microgrids are implemented easily due to the availability of distributed energy sources like nonconventional energy sources (PV cells and fuel cells), energy storing devices like batteries, supercapacitors, etc. can store electrical energy in the form of DC. Hereafter, research is focused towards the implementation of DC microgrids with PV cells, batteries, etc. for satisfying the DC load demand. The deficiency of electricity is one of the main obstacles in the development of rural India. Hence, in the present Indian scenario, stand-alone solar systems are gaining much attention, and they are becoming a very competitive solution, particularly because of the availability of more sunny days throughout the year. One such essential application of PV standalone system is supplying rural areas in efficient way. In India after 2010, DC microgrids are popular with the renewable energy integration for satisfying DC loads in commercial and residential areas. In the case of DC microgrids, solar photovoltaic systems, fuel cells, etc. require the DC supply sources. Out of many renewable energy sources, solar PV systems are low cost, nonpollutant, free available source, and ecofriendly to the environment [1].
Another important feature regarding the DC microgrid is one can easily implement with one or two DC-DC converters, but AC microgrids require a larger number of both DC-DC and DC-AC converters. As a result, DC microgrids required less expensive materials, and also, these grids provide an improved efficiency compared with the AC microgrids. In DC, microgrids are very simple to operate due to the absence of frequency, harmonic distortion and reactive power, and no grid synchronization with the network. In the case of AC microgrids, synchronization of the grid plays a major role. Designing a control structure for DC microgrids is simple w.r.t AC microgrids [4–6].
The proposed work is focused on the application of DC microgrids with DC-DC converters for effective driving of the DC loads as it is shown in Figure 1. Solar energy is preferred as input resource for DC microgrids. PV panel-based solar systems are giving electricity directly from the sunlight, and these PV systems require less space and low cost and give maximum efficiency designed for DC microgrids when compared with the solar thermal collectors. As a result, upcoming research work is carried out on DC microgrids through PV systems to fulfill the DC load demand. The low DC voltage coming from the PV panels cannot drive a high voltage DC applications requirement in DC microgrids.
To enhance the voltage, suitable converters are enabled through PV panel integration, which plays a major role [2]. PV panels allied with DC loads by using isolated or nonisolated DC-DC converters to attain continuous output current and more voltage gain at DC microgrids. By using high frequency (HF) transformer and changing its turn ratio, one can easily get a boost-up voltage at the output side in isolated DC-DC converters [7, 8]. But, it produces voltage ripples, high voltage stress, and leakage currents. Furthermore, very large-size high-frequency transformers are placed in these isolated converters to properly produce an output voltage in the boost module, etc. [9]. But the size of the converter is increased and leads to the bulk in size. Thus, in most of the high-voltage applications, one can prefer nonisolated DC-DC converters rather than the isolated one. In earlier days, traditional nonisolated DC-DC converters are operated with a maximum duty ratio to get high voltage. However, the maximum duty ratio (approximately ranges from 0.85 to 0.95) lowers the efficiency and creates no functionality of the converter. In modern trends, several DC-DC converters to achieve high voltage gain can be used with passive elements [10, 11]. Therefore, a compact size, high efficiency, continuous current etc. are the requirements of economic considerations for DC-DC converters. Several voltage-boosting methods like coupled inductor cascading of converters attaining high output voltage of DC-DC converters with nonisolation are addressed [12–15]. Coupled inductors can control the output voltage based on the inductor coil turns ratio alteration. This coupled inductor leakage inductance produces ripples in the power switch current. To reduce the current spike in the coupled inductor, these converters require a clamping circuit.
In cascaded nonisolated DC-DC converters, the quadratic boost converters (QBC) are the best example to produce output voltage with boosting module in a quadratic manner; however, high voltage stress occurs at power switches and diodes. The high voltage multiplier 2nd order boost nonisolated DC-DC converter is deliberated in [16]. This converter’s output voltage is influenced by the number of voltage multipliers and duty ratio. On the other hand, it generates the less magnitude of the output voltage, though this converter is equipped with a number of voltage multipliers. An active network-based switched-capacitor nonisolated DC-DC converter with high gain is presented in [17]. This converter produces higher voltage gain with poor voltage regulation and pulsating current at the load side. But it gives a discontinuous current at the supply side, which is another drawback. Hence, the converter indicates the utilization of the supply sources in minimum [16–19].
The proposed MSC [20] can overcome the problems of conventional nonisolated and isolated DC-DC converters addressed in [7–19]. This converter can simply operate with one switch that diminishes the difficulty in controlling of gate pulses for the switch [11]. Moreover, it provides continuous current at both supply and load sides, more voltage gain, and the utmost utilization of input resources. Furthermore, it has negligible voltage stress across the diode and switch compared with a novel distinct-switch buck-boost DC-DCSEPIC converter. Hence, it is used for integrated PV-based DC microgrid systems to achieve high efficiency, voltage gain, and continuous output current to the utility grids. PV array with maximum power point tracking (MPPT) is a very important part of the PV system. Researchers develop and implement many MPPT techniques used for PV arrays to generate maximum power and transmit that power to the load to meet the load demand [21]. These techniques are varied w.r.t sensors required, complexity, range of effectiveness, convergence speed, etc. Table 1 can be able to describe the merits of the P&O MPPT technique compared with the other MPPT techniques [22].
The DC-DC converter can effectively utilize in transmitting MPP from the PV array to the load. Through regulating the duty cycle of the pulse width modulation control, the DC-DC converter’s load voltage differs and obtains the MPP with the input source (PV array) to transmit the maximum power. To increase the efficiency of the PV system with an effective MPPT controller is necessary to maintain the operating point of the PV array at the maximum power point in all ecological situations. Therefore, maintaining an MPPT of the PV array mandatorily requires a better MPPT controller with less convergence time and less complexity in its controller algorithm. For this, researchers developed many MPPT techniques such as perturb and observe (P&O) technique, hill climbing (HC) technique, incremental conductance (IC) technique, etc. But most of the researchers used the P&O MPPT technique, which is quite easy, fewer algorithm steps, and also gives a fast response associated with this MPPT controller rather than the remaining other MPPT techniques [22].
In case the PV system meet the load demand in partially shaded conditions and in rainy days, backup should be provided to them with DC microgrids through the battery by using a bidirectional DC-DC converter [BDC]. This article focuses on the half-bridge BDC due to its performance (voltage gain, switch stress, etc.) [23], when compared with the BDCs [9–24]. Here, the proposed BDC is a nonisolated DC-DC converter, and it requires only two switches with three passive elements (two capacitors and one inductor); moreover, it reduces the cost of the converters. When the system with a battery and PV array is used as input sources to the DC, microgrids can effectively satisfy the DC load demand. If the PV system is fully satisfying the DC microgrid system, then the proposed BDC is operated in buck mode to store the DC voltage in a battery. If the PV system cannot satisfy the DC loads in DC microgrid necessities, their BDC can operate in boost mode and make the battery supply a DC voltage to meet the DC loads with their requirements in DC microgrids.
The main aim of the proposed work is to integrate the MSC with DC microgrids to effectively operate the DC loads which are connected through the DC microgrids. Moreover, the high voltage gain and continuous output current produced by this MSC are some of the key features to drive DC loads in DC microgrids in an efficient way. Hence, the motive of this MSC with less passive elements requirement is well suited for the applications of both renewable energy and DC microgrids.
The paper is organized as follows: section II and III elaborated about the performance analysis of conventional SEPIC converter and MSC. The importance of the half-bridge BDC for the PV system-based DC microgrids is addressed in section IV. Discussions on simulation outcomes of the MSC, the half-bridge BDC, the PV system-based DC microgrid with MSC, and the dynamic response of the overall system are viewed in section V. Conclusion of the proposed work is given in section VI.
2. Conventional SEPIC Converter
Conventional or traditional SEPIC converter is also termed as a single-ended primary inductor converter (SEPIC). In general, it is used in the high-voltage renewable energy applications. But the problem associated with this converter is listed as follows: (1)It produces less voltage gain(2)It generates ripples at the output side (load side) when this converter takes input voltage with some noise signals(3)This converter does not properly utilize input resources in the required manner
The difficulties related with this conventional SEPIC converter are overcome with the MSC discussed in section III. Moreover, conventional SEPIC converter needs extreme duty ratio to operate a converter in a boost mode. Thus, it affects the efficiency and functionality of the system when operated at the maximum duty ratio. But MSC does not need any maximum duty ratio point, and the converter operates in boost mode with a duty ratio of 0.55 to 1 in an efficient manner without producing any unwanted disconcerting signals. The circuit diagram of the conventional SEPIC converter shown in Figure 2 operates like a buck-boost DC-DC converter, but it continuously generates output current.
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3. Modified SEPIC Converter
MSC includes input-output terminals and derivatives by changing the conventional SEPIC converter presented in Figure 2. Elaborated operation of the MSC is shown in Figure 2(b) using switch S by means of switching frequency () with other elements like diodes, inductors, and capacitors. The capacitor and inductor act as the voltage-boosting components by adding a , diodes in MSC. Proposed MSC merits are as follows: (1) MSC operates by a single power switch that decreases the difficulty of controller circuitry. (2) This converter produces input current without any distortions. (3) It gives more gain w.r.t voltage. (4) MSC utilizing the sources effectively on input.
Therefore, MSC-integrated PV system-based DC microgrids are proposed. Few assumptions are considered to evaluate the steady-state operation of the MSC at ideal, and all capacitors are large and sufficient to attain constant voltage. The modified SEPIC converter can operate in 2 modes to obtain the continuous output current as shown in Figures 3 and 4.
3.1. Mode 1 ()
Mode1 3 inductors are attaining the following current path when these inductors are magnetized: inductor current follows the path from source voltage and showed with a red dotted line path (Figure 5(a), 1A). Second current flows from capacitor path shown in Figure 5(a)), 1B, and flows from capacitor , and it follows the path as 2 as shown in Figure 5(a). At this juncture diode is reverse biased by capacitor and transfers the energy to the DC load.
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In Mode 1 (1) , is the voltage across capacitors , , whereas , , and are the voltages across inductors , , and , correspondingly.
3.2. Mode 2 ()
At mode 2, 3 inductors are attained following current path when these inductors are magnetized: with source voltage () charges the and follows the path , , , ,and . and charge to capacitor as flows from , , , , and . Succeeding inductor discharges over the DC load follows the path , , shown in Figure 5(b).
In mode 2, is the voltage across capacitor . As per the volt second balance equation for the inductors , , and ,
Using Equation (8) to analyze the voltage gain for the proposed converter is achieved by varying the duty ratio from 0.6 to 0.9 as follows. When is 0.6, 0.7, 0.8, and 0.9, the corresponding voltage gains are 3.75, 7.78, 20, and 90. Hence, high voltage gain is obtained when the duty ratio is increased. From Table 2, only one controlled switch is enough to obtain the high gain in voltage with low voltage stress relating to the other converters. Due to more voltage gain of the proposed MSC, it can be preferable for DC microgrid applications.
4. Half-Bridge BDC
Nonisolated BDCs are essentially understood by the addition of a diode and an antiparallel diode to the switch of the unidirectional converter connected with a controllable power switch. Basically, buck, boost, buck-boost, SEPIC, and CUK DC-DC converters make some nonisolated BDCs when the diode in the above DC-DC converters is interchanged with a controllable power switch. Based on the voltage boosting methods, nonisolated BDCs whereas interleaved multilevel, switched capacitor, etc., Table 3 shows that half-bridge configuration type nonisolated BDCs are the most capable, high-proficient, and robust in configuration, and also, these BDCs give the high voltage gain compared with the other nonisolated BDCs.
Commonly, this BDC can work in both synchronous boost and buck modes for power flow in both forward and reverse directions. The working operation of the converter is described in 2 modes. When power switch P is turned on with the help of a required duty ratio control, the operation of this BDC is viewed in a forward step-down mode. When Q is turned on, then P is turned off with the help of a proper controlling duty ratio, this BDC can undergo a backward step-up operation as shown in Figure 3.
This BDC requires only two switches with three passive elements (one inductor and two capacitors). While comparing this BDC with conventional BDCs, this BDC has wide voltage gain; especially in boost mode, the cost of this BDC is less, and also, this BDC generates continuous output current without ripples. Generally, this converter operates in two modes, buck mode and boost mode.
5. Simulation Results and Discussion
Figure 6 shows the two input sources such as PV source and battery with half bridge BDC; here, the DC microgrid consists of DC loads. These blocks are connected to the MSC. MSC probably produces an effective DC voltage and current to the DC loads in DC microgrids from the PV source. If in case partially shaded conditions happened, PV panels do not supply the voltage required by the DC microgrid. For backup protection and to balance the supply voltage and currents with load voltage and currents, BDC with battery is required. Here, half-bridge BDC is used to supply voltage to the DC loads if in case PV does not satisfy the amount of voltage required by the DC loads.
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5.1. Simulation Results of the MSC
Generally, MSC can produce wide voltage gain with continuous output current. Moreover, this MSC always uses the resources at the maximum level. It extensively produces the voltage gain with better efficiency. Usually, it is effectively operated by a fixed frequency and variable duty along with the PWM technique to generate a gate voltage to the power switch. The proposed MSC is successfully simulated in PSIM software and generates the output voltage at a higher voltage gain with the preferred output current required by the DC load. Here, this MSC, PSIM results are obtained without producing ripple content in its output voltage and current. Hence, it is well suited for DC microgrids and PV system applications. But conventional nonisolated DC-DC converters produce ripples in the percentage of 0.1%-0.5%. But MSC produces ripple content in the percentage of around 0.016. This ripple voltage is a negligible value. Therefore, it effectively produces output voltage without producing any ripple content in output voltage and current. The values of the passive and active parameters used in this entire project are viewed in Table 4.
Figure 6(a) describes the supply voltage, output voltage, and current of MSC as 24 V, 186.3 V, and 0.5A, respectively. These three waveforms are periodically DC in nature. Here, MSC cannot generate any ripple content in the output voltage and current. Thus, MSC always generates continuous current to the DC loads. Figure 6(b) shows that inductor , , and current regarding the MSC with values of 4.2 A, 1.4 A, and 0.5 A (average) current, respectively. In mode I, currents flowing in three inductors are increasing with a positive slope and vice versa in mode II operation.
Figure 7(a) illustrates the capacitor voltages and , and the corresponding values are 78.71 V and 76.75 V. It is examined that approximately +80 V is obtained across the capacitors and . It is analyzed that the characteristic waveforms and this simulation results of capacitor voltages and are matched and steady state in nature (Figure 7(a)), current flowing in the capacitor with the value of 0.5A (average value). The average current of this capacitor is exactly equal to the output current flowing in the resistor R. Figure 7(b) elaborates the diodes , , and blocking voltages in reverse bias condition. During mode 1, diodes and are in forward bias condition, and these diodes generate peak inverse voltages similar to the capacitors and , and the corresponding values are 76 V and 184 V. It is shown in Table 5 that during mode 2 operation, peak inverse voltage is the same as the output voltage () around 186.3 V, which is obtained when diode is under reverse bias condition. Figure 7(b) also shows the switching pulse voltage of the MSC. Generally, every DC-DC converter is taking pulse voltage from the pulse generator based on its duty ratio control. Here, MSC’s power switch also takes pulse voltage from the pulse generator with 70% duty ratio.
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5.2. Simulation Results of the Half-Bridge BDC
Here, is a supply voltage, and and are the output voltages of a half-bridge BDC operated in buck or boost modes with the following values: Vs is 24 V and Vo and Vo1 are 20 V and 48 V, which are shown in Figure 8(a). Based on the output voltages produced, the results are proving the feasibility of this BDC, which is effectively well integrated to the DC microgrids and feeds DC voltage to the DC loads in a reliable manner. Here, half-bridge BDC is operated in two modes. The first mode is a buck mode; in this mode, this BDC generates the output voltage with the value of 20 V (average value). The second mode is a boost mode; in this mode, this BDC generates an output voltage with the value of 48 V. The output voltages of this BDC are determined by the duty ratio of 50%.
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5.3. Simulation Results of the PV System-Based DC Microgrid Operated with Half-Bridge BDC in Buck Mode
Operation of the PV system-based DC microgrid with half-bridge BDC in buck mode, one can easily achieve the load demand with the help of the PV system with MSC. Here, is a supply voltage of 24 V. And is the supply or input current with 18.6 A. And this supply current is effectively satisfying the three DC load currents; is 8.1 A, is 8.1 A, and is 2.4 A. So, here, . And DC bus voltage across the DC microgrid is 183.5 V when MSC is simply triggered with a duty ratio of 0.7. Here, , , and are the DC voltages across the three DC loads with values of 12 V, 24 V, and 24 V. But here, the half-bridge BDC simply operated in a buck mode can act as a third DC load. Moreover, this DC load will always be supplied by the input resource called the PV system. Here, calculate the supply current ripple of the PV system-based DC microgrid operated with half-bridge BDC in buck mode,
Here, the negligible ripple in supply current of the PV system-based DC microgrid operated with half-bridge BDC in buck mode. At this stage, the whole system is effectively satisfied with all three DC loads. Thus, effective supply voltage and current can reach the three DC loads in an effective manner. Figure 8 shows the DC currents , flowing in the half-bridge BDC in buck mode of the PV system-based DC microgrid operated with half-bridge BDC. During buck mode, obtained current values are 7.55 A and 7.3 A.
Figure 9 shows that current flowing , dc bus voltage , DC voltages , , and voltage of the half-bridge BDC in buck mode of the PV system-based DC microgrid operated with half-bridge BDC in buck mode with the values of 3.1 A,183.5, 12 V, 24 V. Here, these three voltages are appearing as an output voltage of the DC load ends which are connected to the DC microgrid. Calculated dc bus voltage ripple of a of the PV system-based DC microgrid operated with half-bridge BDC in buck mode. Equation (11) shows that negligible voltage ripple occurred in dc bus voltage be noticed that with the help of MSC, the PV system effectively serves the dc loads which are connected in a DC microgrid without generating any current or voltage ripples in the mode of the PV system-based DC microgrid operated with half-bridge BDC in buck mode. The input power supplied by the PV system with the help of the MSC effectively satisfy all three dc loads’ output power connected in DC microgrid. In this mode, 12 V to 24 V DC loads effectively utilized the output power produced from the integration of the PV system with MSC, and the parameters are given in Table 6.
From Table 4, three substituting values of the parameters specified in Equation (14) are
By means of the numerical analysis, this PV system-based DC microgrid operated with half-bridge BDC in buck mode with the application of MSC can generate the input power more than the load requirement without generating any fluctuations in output power.
5.4. Simulation Results of the PV System-Based DC Microgrid Operated with Half-Bridge BDC in Boost Mode
In this operation of the PV system-based DC microgrid operated with half-bridge BDC in boost mode, one can easily achieve the load demand with the help of the PV system and half-bridge BDC operated in boost mode with MSC. Here, and are supply voltages with the value of 24 V and 40 V. And and are supply or input currents with values of 2.4 A and 16.6 A. These supply currents are effectively satisfying the two DC load currents; is 8.4 A, and is 8.2 A. Therefore, DC bus voltage across the DC microgrid with 183.76 V when MSC is simply triggered with a duty ratio of 0.7. Here, and are the DC voltages across the three DC loads with values of 12 V and 24 V. But half-bridge BDC simply operated in a boost mode can act as a supply system with a battery source. Moreover, these DC loads are always supplied by the input resources called by the PV system and battery with half-bridge BDC operated in boost mode.
Figure 10(a) shows that dc supply currents and current flowing in the half-bridge BDC in boost mode of the PV system-based DC microgrid operated with half-bridge BDC in boost mode with the values of 3.4 A and 23 A. These two currents are supply currents to the PV system-based DC microgrid operated with half-bridge BDC in boost mode.
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Here, the calculated current ripple of the half-bridge BDC in boost mode is given as
Here, the negligible ripple in current is achieved by the PV system-based DC microgrid operated with half-bridge BDC in boost mode. At this juncture, the whole system effectively satisfied all two DC loads. As a result, this effective supply voltage and current can reach the three DC loads effectively. Figure 10(a) also shows that DC, and , of the PV system-based DC microgrid operated with half-bridge BDC in boost mode with the values of 13.2 A and 13.2 A. Here, these two currents are feeding the dc loads. Figure 10(b) shows the voltage of the half-bridge BDC in boost mode of the PV system-based DC microgrid operated with half-bridge BDC in boost mode with the value of 40 V when the supply voltage is given as24 V. Here, these two voltages are appearing as supply voltages of the PV system-based DC microgrid operated with half-bridge BDC in boost mode. Here, the calculated dc bus voltage ripple of the PV system-based DC microgrid operated with half-bridge BDC in boost mode.
From Equation (18), the negligible ripple in dc bus voltage is obtained from the PV system-based DC microgrid operated with half-bridge BDC in boost mode. Therefore, the whole system effectively satisfied all two DC loads. Hence, supply voltage and current can reach the two DC loads effectively.
Figure 10(b) also shows that dc voltages and of the PV system-based DC microgrid operated with half-bridge BDC in boost mode with the values of 24 V and 48 V. Here, these two voltages are appearing as an output voltage to the dc loads which are connected DC microgrids. Here, one thing to notice is that with the help of MSC, a PV system and energy storage element connected with the help of a half-bridge BDC can effectively serve the dc loads which are connected in a DC microgrid without generating any current or voltage ripples in the mode of the PV system-based DC microgrid operated with half-bridge BDC in boost mode. The input power supplied by the PV system and energy storage element connected with the help of a half-bridge BDC with the help of the MSC effectively satisfy the two dc loads output power connected in DC microgrid in this PV system-based DC microgrid operated with half-bridge BDC in boost mode. In this mode, 24 V to 48 V DC loads effectively utilized the output power produced from the integration of the PV system with MSC, and parameters are described in Table 7.
Neglecting the losses (switch and diode power losses),
From Table 5, the substituting values of the parameters specified in the above equation are
Based on the numerical analysis, this PV system-based DC microgrid operated with half-bridge BDC in boost mode with the application of MSC can generate the input power more than the load requirement without generating any fluctuations in output power. This entire paper elaborated about the implementation of a modified SEPIC converter with DC microgrids for effectively satisfying the DC loads in an efficient manner. Moreover, this converter can effectively operate with PV system to obtain the maximum voltage gain. Here, input voltage with disturbances is feed to the MSC. And then output voltage of MSC is producing some transients in its output voltage waveform. Here, performance parameters under time domain specifications are evaluated for the open loop control of MSC’s output voltage.
5.5. Dynamic Response of the System against the Environmental Conditions
This section describes the overall performance of the system against all environmental conditions. The research scholars know that the PV system voltage is varying with respect to any climate Conditions (1). To eradicate this problem with the help of the proposed MSC, the proposed MSC can produce constant output voltage when it takes varying input voltage also. The reason behind this is that the proposed MSC can effectively utilize the input resources in a greater way [20]. So, the following PSIM simulation-based results are evident for the proposed MSC which effectively has a good dynamic response regarding the control of DC microgrid loads. Figures 11(a) and 11(b) prompt the input current and voltage waveforms of the open loop control of MSC. Here, input current is 4 A, and the input voltage is 24 V of the open loop control of MSC. These waveforms regarding the open loop control of MSC are having some disturbances. Then, these input currents and voltage are fed to MSC, and finally, output voltage and current of open loop MSC are viewed at DC loads driven by MSC.
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Figure 12 can illustrate the open loop MSC’s output voltage waveform, damping ratio , undamped natural frequency , and damped natural frequency parameters are calculated with the help of the logarithmic decrement method [25]. Damping ratio , undamped natural frequency , damped natural frequency =1.03 rad/sec, and here,.
The mathematical calculations described in Table 8 demonstrate that the peak overshoot value is 6.30%, delay time, peak time, and rise time are at less than 3 sec, and finally, the settling time is at 4.67 sec regarding the output voltage of the open loop control of MSC. If MSC’s output voltage can be controlled, the output voltage of this MSC definitely produces no transients and has a peak overshoot nearly at 6%, and the settling time of this output voltage waveform is nearly at 5 sec. So, these values prove that open loop control of MSC can generate constant DC output voltage in the period of less than 0.1 sec in Figure 13. So, that is the reason closed-loop control of MSC is implemented to generate a constant output voltage and current for DC microgrid loads driven by MSC.
6. Conclusion
The MSC topology for PV system-based DC microgrids is discussed and simulated using PSIM software. The advantages of using MSC topology are addressed. PV system with an MSC configuration continuously generates output current without producing any ripples. This configuration gives the output voltage with high gain, delivers the required amount of power supply demanded by the DC loads, and achieves a reliable power supply to the DC loads by using the integration of an MSC-based PV system. And the dynamic response of the overall system is also presented, especially this topology which is well suited for domestic applications. Nowadays, most of the houses are equipped with DC LED lamps, BLDC motor-based ceiling fans, etc. These applications require DC supply. Domestic appliances which are operated by the DC supply definitely satisfy their load demand when they are using the topology addressed in the proposed work.
Data Availability
Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.
Conflicts of Interest
The authors declare that they have no conflicts of interest.